Search

EP-3114183-B1 - ADHESIVE-COATED THERMALLY SENSITIVE POLYMER SUBSTRATE, PROCESS FOR ITS MANUFACTURE AND USE THEREOF

EP3114183B1EP 3114183 B1EP3114183 B1EP 3114183B1EP-3114183-B1

Inventors

  • MUNDT, STEFAN

Dates

Publication Date
20260506
Application Date
20140305

Claims (7)

  1. Process for the manufacture of an adhesive-coated polymer substrate comprising: (a) a polymer substrate containing: a thermoplastic polymer with a Vicat A50 softening point according to DIN EN ISO 306 of up to 170°C; a plasticizer; and, carbon black pigment; and, (b) an adhesive composition coated directly on at least one side of the polymer substrate, wherein the adhesive composition (b) is a UV-cured hot melt pressure sensitive adhesive (PSA), said process comprising the steps of: (i) providing the polymer substrate having a thickness from 30 to 300 µm; (ii) coating directly a UV-curable hot melt pressure sensitive adhesive (PSA) on at least one side of the substrate; and, (iii) curing the adhesive composition (b) by irradiation with UV light by a low pressure mercury lamp as a UV-C radiation source, wherein said UV-cured hot melt adhesive (PSA) is obtained from the corresponding UV-curable hot melt adhesive (PSA) by irradiation with a UV light source such that the temperature at a distance of from 15 to 50 mm next to the surface of the coating of the UV-curable hot melt adhesive on the substrate does not exceed an upper temperature T max of 120°C.
  2. Process according to claim 1, wherein the temperature at a distance of from 15 to 50 mm next to the surface of the coating of the UV-curable hot melt adhesive on the substrate does not exceed an upper limit temperature T max of 100°C in the range of from 15 to 50 mm next to the surface of the coating of the UV-curable hot melt adhesive on the substrate.
  3. Process according to claim 1, wherein the low pressure mercury lamp emits only light with a peak maximum at 254 nm.
  4. Process according to any one of claims 1 to 3, wherein the UV-curable or UV-cured hot melt PSA contains an acrylic copolymer or a synthetic rubber copolymer.
  5. Process according to claim 4, wherein the acrylic copolymer comprises a mixture of alkyl(meth)acrylates which comprises from 0.1 to 30 weight-%, based on the mixture, methyl(meth)acrylate.
  6. Process according to claim 4 or claim 5, wherein the acrylic copolymer comprises a mixture of alkyl(meth)acrylates which comprises 70 to 99.9 weight-%, based on the mixture, of C 2 to C 18 alkyl(meth)acrylates, preferably C 2 -C 10 alkyl(meth)acrylates, more preferably n-butyl acrylate, ethyl acrylate and/or 2- ethylhexyl acrylate.
  7. An adhesive-coated polymer substrate comprising: (a) a polymer substrate having a thickness from 30 to 300 µm and containing a thermoplastic polymer with a Vicat A50 softening point according to DIN EN ISO 306 of up to 170°C, a plasticizer, and carbon black pigment; and, (b) an adhesive composition coated directly on at least one side of the polymer substrate, wherein the adhesive composition (b) is a UV-cured hot melt pressure sensitive adhesive (PSA), prepared by a process as defined in any one of claims 1 to 6.

Description

The invention relates to an adhesive-coated thermally sensitive polymer substrate, a process for its manufacture and the use thereof. The invention relates in particular to an adhesive-coated thermally sensitive polymer substrate, wherein the thermally sensitive polymer substrate contains or consists of a thermoplastic polymer with a VICAT A50 softening point according to DIN EN ISO 306, of up to 170°C, a preferred process for its manufacture and the use thereof. Thermally sensitive film, in general made of a thermoplastic polymer, could so far not be directly coated with a UV-curable hot melt pressure-sensitive adhesive (PSA) (in the following to be referred to as "hot melt PSA") and cross-linked. Already in the course of coating the substrate with a non UV-curable hot melt PSA, the films are often thermally damaged at the usually applied temperatures of about 160 - 180°C. More importantly, at the latest in the curing or cross-linking step, when the UV-curable hot melt PSA is cross-linked upon irradiation with UV light of a common UV source, the films are thermally heavily damaged or even burnt. In particular films that have been pigmented with carbon black are burning off because of the infrared absorption of carbon black and the strong evolution of heat when cross-linking is performed with a customarily used medium pressure UV mercury lamp. As a result, it was therefore until now impossible to produce for example black PVC insulating tapes that are coated with a UV-cured hot melt PSA. Various attempts have therefore been made to deal with these heat associated problems when thermally sensitive substrates such as those made of soft PVC are used. EP 1 693 428 B1 relates to a backing film for adhesive tape of the hot-melt type based on bisoriented polypropylene (BOPP), comprising in succession at least one layer comprising polypropylene or a mixture of polypropylene resins, an opaque layer and a layer of a polyamide-resin based lacquer. This invention is concerned with the problem that the relatively high temperatures required by the holt-melt technique require the use of an adequately heat-resistant backing film, for example one based on bisoriented polypropylene, ruling out the use of the hitherto most commonly used material for this purpose, polyvinyl chloride (PVC). EP 1 528 091 B1 describes a pressure-sensitive adhesive tape comprising a support and an adhesive layer or adhesive layers made of an adhesive agent comprising a base polymer and cross-linking agents on a single surface of the support or on the surface and the other surface thereof, wherein the support comprises soft polyvinylchloride comprising a plasticizer, and at least the adhesive agent on the single surface comprises, as a base polymer, an acrylic copolymer having a carboxyl group, and further comprises, as the cross-linking agents, a mixture of cross-linking agents comprising an isocyanate type cross-linking agent, a glycidylamine type cross-linking agent, and a melamine type cross-linking agent. DE 101 05 278 A1 (BASF SE) describes a mixture containing: a) a polymer, which consists to an extent of at least 40 wt.% of C1-C18 alkyl (meth)acrylates (polyacrylate); and, b) a homopolymer or copolymer of vinyl alkyl ether (polyvinyl alkyl ether), which consists to an extent of at least 70 wt.% of structural units of the following formula-CH2-CH(XOR)-, in which: X stands for a covalent bond or a C1-C3 alkylene group; and, R stands for a C1-C6 alkyl group. An object of the present invention is therefore the provision of an adhesive-coated thermally sensitive polymer substrate, wherein the adhesive is a UV-cured or UV-curable hot melt pressure sensitive adhesive (PSA) ("hot melt PSA"). Another object of the present invention is to provide a process for the manufacture of such an adhesive-coated temperature sensitive polymer substrate and a use for the adhesive-coated thermally sensitive polymer substrate. Accordingly, the present invention is directed to a process for the manufacture of an adhesive-coated polymer substrate comprising: (a) a polymer substrate containing: a thermoplastic polymer with a Vicat A50 softening point according to DIN EN ISO 306 of up to 170°C; a plasticizer; and, carbon black pigment; and, (b) an adhesive composition coated directly on at least one side of the polymer substrate, wherein the adhesive composition (b) is a UV-cured hot melt pressure sensitive adhesive (PSA), said process comprising the steps of: (i) providing the polymer substrate having a thickness from 30 to 300 µm; (ii) coating directly a UV-curable hot melt pressure sensitive adhesive (PSA) on at least one side of the substrate; and, (iii) curing the adhesive composition (b) by irradiation with UV light by a low pressure mercury lamp as a UV-C radiation source, wherein said UV-cured hot melt adhesive (PSA) is obtained from the corresponding UV- curable hot melt adhesive (PSA) by irradiation with a UV light source such that the temperature at a dista